1. Field of the Invention
The present invention relates to an image forming apparatus such as a copier or a printer, and more particularly to a technique of cooling heat sources inside the image forming apparatus.
2. Description of the Prior Art
With a copier or other image forming apparatus, an exposure lamp of an exposure device for exposing a surface of a photosensitive material, and fixing rollers for fixing a toner image to recording paper may become heated to a degree to adversely affect other components. Therefore, air is drawn into the main body of the apparatus from outside to cool the exposure lamp and fixing rollers, and the air having been used for the cooling purpose is exhausted from the main body.
On the other hand, in the image forming apparatus as noted above, ozone is generated by electric discharges from a main charger for charging the surface of the photosensitive material and from a transfer and separating charger for transferring the toner image from the surface of the photosensitive material to the recording paper. Further, toner particles, paper particles, oil mist and other such dust are scattered in the regions of a developing device and a cleaning device, for example. Thus, harmful substances such as ozone and dust are afloat inside the apparatus.
When the air used in cooling the exposure lamp and fixing rollers is exhausted from the apparatus, the ozone, dust and other harmful substances afloat in the apparatus will be discharged with the air outwardly of the apparatus. This gives rise to the problem of polluting the environment adjacent the apparatus.
More particularly, very high temperatures prevail in the vicinity of the fixing rollers or a flash fixing device for fixing the toner image by heating and in the vicinity of an optical system for scanning a document image with a halogen lamp or the like. In order to cool these components it is necessary to draw large quantities of air into the apparatus and discharge the air outwardly thereof. This results in a secondary problem in that the harmful substances such as ozone and dust inside the apparatus are inevitably discharged with the cooling air.
Such harmful substances will be generated in the apparatus even if harmful substance removing filters are provided where the harmful substances are generated as noted above, since the filters have limited capabilities and their capabilities deteriorate with lapse of time. Such harmful substances are readily exhausted from the apparatus by a cooling mechanism that produces ample air flows.
In the conventional apparatus as noted above, no concept has been employed for separating air flows of the cooling system and those for removing ozone and other harmful substances. Thus, it has been impossible to sufficiently reduce the chances of the harmful substances flowing out of the apparatus.